Master Gardener: Brown rot can attack peach and other stone fruits

Q. Blossoms and leaf clusters on my peach tree have shriveled and browned. This doesn’t look like peach tree leaf curl. Any ideas?

A. What you have sounds like brown rot (Monilinia spp), a fungus that attacks almond, nectarine, apricot, plum, cherry and quince as well as peaches.

Blossoms, twigs and leaves shrivel and die. Gummy ooze may appear at the bases of dead flowers. Sunken brown areas (cankers) may develop around twigs near the flowers. After harvest the ripe fruit can also develop brown rot fruit rot.

The rot spreads rapidly by spores within a day or two. The fungus survives the winter on diseased twigs and old, rotted fruit (mummies) on the tree or on the ground. Air currents, insects and rain splash spread the spores. These then infect flowers of the new year’s crop.

Prompt removal and destruction of the diseased plant parts prevents buildup of brown rot inoculum in isolated trees and small orchards, and may keep it below damaging levels. Prune the trees to keep an open canopy and allow good ventilation. Avoid wetting blossoms, foliage and fruit when you irrigate. If you can, plant brown rot resistant varieties. After the leaves drop, prune out branches with fruit and nut mummies and burn or bag these. In the spring bloom period check for the fungus again, remove whatever’s infected, and destroy or bag it.

The Shasta Master Gardener Program can be reached by phone, 242-2219, or email mastergardeners@shastacollege.edu. Master gardeners are also at the Redding Farmers Market on Saturdays.